The significance of the plat map is often overlooked in community associations. Put simply, the plat is a graphical depiction of lot boundaries, easements and other ownership interests. Here's an example:
This is a plat map for a planned unit development subdivision. Condominium plats are slightly different, and include building elevations, unit boundaries, and common elements locations.
Notations on plats are important, too. Examples of notations include: maintenance obligations, common area ownership, and utility company easements. These notations are just as significant and important as provisions in your CC&Rs.
Now that you know how important your plat map is, you may be wondering how counties or municipalities keep track of who owns what and where property is located. Plats contain very specific location information, starting with township, then range, and then section, like this:
We can tell that the subdivision is located in the east 1/2 of Section 28, Township 1S, Range 1E, W.M. (Willamette Meridian). This coordinate system is attributed to Thomas Jefferson, and was formalized in the Land Ordinance Act of 1785. The Act called for the creation of townships 6 miles by 6 miles, with 36 square sections containing 640 acres. Every township referenced a meridian, like the image above, which references the Willamette Meridian.
If you don't have a copy of your plat, many county recorder or survey offices provide the files online. Here are links to access your plat map in the tri-county area:
Multnomah County: https://multco.us/surveyor/sail-survey-and-assessor-image-locator
Clackamas County: http://www.clackamas.us/surveyor/